Composers and sound artists have explored for decades how to transform microphones and loudspeakers from inaudible technology into genuinely new musical instruments. While the sound reproduction industry had claimed perfect high fidelity already at the beginning of the twentieth century, these artists found surprising ways of use for instance tweaking microphones, swinging loudspeakers furiously around, ditching microphones in all kinds of vessels, or strapping loudspeakers to body parts of the audience. Between air and electricity traces their quest and sets forward a new theoretical...